With the rapid development of communication technologies, high speed, large capacity, and wide coverage have become main features of a modern communications system. Currently, an MU MIMO (Multi-User MIMO) technology has become one of core technologies of mainstream wireless communications standards such as LTE (Long Term Evolution) or LTE-A (LTE-Advanced).
In an MU MIMO system, spatial multiplexing of data streams of multiple users is implemented by using a precoding technology, which may greatly improve spectral efficiency and a capacity of the system. Design of a pilot provides guidance for a receiver to try its best to obtain a channel that has relatively low inter-user interference, so as to correctly receive data. In an LTE standard, multiple pilots used in the MU MIMO system are orthogonal to each other in a code division manner or in a code division and frequency division manner, so that the receiver can obtain “clean” channel information no matter whether interference exists between multiple streams in the system. Currently, eight orthogonal pilots defined in the standard can support concurrent transmission of a maximum of eight data streams, and overheads of the eight pilots have occupied 14.3% of all transmission resources.
However, as paired data streams of the MU MIMO system increase, a quantity of orthogonal pilots that are required by the system will also increase accordingly, and an overhead of the increased pilots will occupy transmission resources of useful data.